Logging a message

All WSGI applications can write messages to an error log. The wsgi.errors environ key is an open file object for writing errors. You can use it in Pylons like this:

The above example would write the message This is an error! to the error log unchanged with no preceding or following whitespace.

Pylons also comes with a helper function called log() which logs messages to the WSGI error object in a formatted manner. You use it like this:

This would produce the following:

=> This is an error

The log message is preceded by => and followed by a line end.

Using a Log file

Your log messages will be sent to wherever the error file like object is set to store them in the WSGI environment you are using.

If you are using paster serve then they will be logged to the stdout with the other server messages. paster serve also has a --log-file=LOG_FILE option which can be used to specify a log file to which to write the error messages.

For example, supposing you wanted to serve the configuration development.ini and log messages to a file called myapp.log, you could do the following:

paster serve --log-file=myapp.log development.ini

This option suppresses the output to stdout and instead writes it to the file myapp.log.